1. Field of the Invention
The present invention relates to roof ventilation devices for venting the underside of a roof structure to the outside thereabove.
2. History of the Prior Art
It is well known in the construction of roof structures to provide such structures with ventilation arrangements so that the underside thereof is vented to the atmosphere above. Such venting prevents the unwanted accumulation of moisture at the underside of the roof structure and other undesirable effects which may occur in the event the roof structure is left unvented.
Desirably, a ventilation air flow path is established between eave vents at the lower edges of the roof and ridge vents located adjacent the peak of the roof and within the attic space below the roof. Wind blowing across the roof creates a vacuum or venturi effect to draw air through the eave vents and force air out of the ridge vents. With no wind, ventilation still occurs as warm air rises within the attic space and exhausts through the ridge vents, thereby drawing fresh air through the eave vents.
In typical prior art arrangements for venting roof structures, the roof support structure on which a plurality of tiles or shingles are mounted is provided with one or more apertures to vent the space therebelow. The apertures are in turn vented to the atmosphere above the roof structure by the use of devices which provide air passages to the outside of the roof from the apertures in the roof support structure.
Examples of prior art roof ventilation devices are provided by U.S. Pat. Nos. 4,899,505 of Williamson et al., 2,905,072 of Oswald, and 938,930 of Wiest, and by U.K. Patent No. 2,145,131, U.K. Patent Application No. 2,199,860 and U.K. Patent Specification No. 593,645. The Wiest patent describes a concrete shingle having spacers and fluid passages which cooperate with apertures in the roof support structure to vent the roof structure. The U.K. '645 patent specification describes a ventilation device disposed between adjacent shingles, while the Oswald patent and the U.K. '860 patent application describe ventilation devices which replace an entire shingle or tile in a wall or roof structure. In Oswald, the ventilation device has moisture drain holes at the bottom thereof as well as a screen to keep out vermin. In the U.K. '860 patent application, a fly screen is employed to keep out insects and vermin, while the Williamson patent describes openings and slots which are configured to keep out rain water. The U.K. '131 patent provides yet another example of a roof ventilation device.
While the various roof ventilation devices described in the patents, applications and specifications noted above function to ventilate the various roof and wall structures thereof, such devices leave much to be desired in terms of their lack of desirable features. One of the main disadvantages of such devices is their inability to integrate with the roof structure in such a way that they form a part of the tiles, shingles or other product of the roof structure. Ideally, the roof ventilation device should integrate with and form a part of the product in a manner which provides effective ventilation while at the same time not disturbing the appearance and continuity of the tiles, shingles or other product forming the upper portion of the roof structure. The roof ventilation device should also be capable of securing adjacent portions of the tiles or shingles in place. In addition to ventilating the roof support structure to the atmosphere above the roof structure in an effective manner, such roof ventilation devices must also be effective in preventing the entry of rain water, insects, vermin and debris into apertures in the roof support structure. Desirably, such devices should be effective in preventing entry of rain water in deluge conditions and when the rain is wind driven such as in severe storm or hurricane conditions.